Means for supplying pulses of modulated current



Patented Mar. 9, 1948 v MQDULATED CURRENT V Paul N. Bos sa'rtyCheswick, Pa., assignorto'i lhe Y-Union Switch & Signal Company, Swis'svale,

Pa.,;a corporation of Pennsylvania hmiii'catio ju e 22, 1945, Serial No. 600,899

through the-telephone receiving a paratus. -'Also,/

arelatively simple and reIiabIe construction of the supplymeansis"desirable;

Accordingly; a feature of m invention is "the provision "of novel -means=for suppl ing current ofa preselected characteristice---- y Another feature ojf m'yf fin-vention is the previs'ion of novel and "improved-means for supplying pulses of modulated current andwhich current is adaptable to-being used with telephone equipm nt s v V .7 -A more specific feature of my invention-is the provision of novel andirrllorove'd "means for supplying pulses of 'frequency rnodulatedcarrier current which areadaptabIeto-being used with train telephone eommunicatidnequlpment of the carrier type using f-re'quen'cy modulation.

Ag-aim-a fe'ature- 6f niy rivn'tio'n 'is the provisionof novel-meanscf rl'atively simple and inexpensivestructuredor siipplying pulses of modulatedcurrent. .Oth'er features, object and-advantages of my invention will appear his the specification progpess'es c a i 'Ihe foregoing- 'featuresg objects and advantages embodying 1 my invention I attain by the -provi- 510 11 of: means including-vibrators r: interrupters to iinipulse s'e'xcite tuned circuits .irom- Ia direct current source :Inithis wlay pulses for trains of oscillations twin :flew in the .tunedfeircuit in responsewto" each impulse iorfshock -excitation of the tuned-scircuit. vThe tuned circuit includes, or has electricallyassociated therewith, means for varying the ii'eactance-aof the. circuit at "a rate corresponding to-1a 'given-rsignaband in this way oscillationssofythetuned circuit are modulatedaceord-i g to suchsignal,

in a preferred .dfFthe:-invention ;I provide trig-vibratorsof differentrates ofivibration. One vibrator operates-at relatively;- ;high rate of here ics a d impulse-excites a c euit'stuned. to resonance at a preselected carrier-frequency, "and 114' Claims. (01. 179-1715) which circuit includes a windinglmou'nted en a closed iron core-structure ofeaitransformer A second vibrator-or. interrupter operates at a relatively low rate'ofqvibration'and impulse excites a circuit tuned to resonance at apreselected audio frequency and which qlatter lcircuit :includes \another winding mounted, enthe transformerecore structure. Each pulse or train of audio frequency oscillations serves to vary the permeability of the core structure and; thereby modulate the carrier frequency oscillations. To increase the amount of change of the opermeability-ofthecore structure, a direct current polarizing winding is-preferably mountedomthe core and energizedirom -.a direct current source, *A-secondar-yor--output winding of the transformer 1oosely-couples the transformer to a loa d-circuit or element. Since there is no iflxed ph-ase relaticnshiptbetween the two vibrators, the'pul'se supplied too-the output circuit will ber-oficarrienfrequencies varied over a range predetermined-by- .the :change ;of inductance of the transformer in response -i-to the modulating-frequency currents =This 15150 because the excitation of the audio tuned circuit causes the flux of the iron core-and therefore the permeabilityo ofnthercore, to be -varied at the resonant frequency. of :the circuit, rand the carrier frequency willbe variededue to such change in the permeability of the iron core; Such pulses or trains of frequency modulated current delivered to the load circuitwill follow-in-rapid succession at a rate corresponding toe-the rate of-vibratiqn of the high vibrator and thesetpulses will beof a characteristic that will be-heard in the loudspeaker of receivingapparatus capable of-receiving such frequency modulated carrier telephone current. r

In another form 1101 the invention, the reed: or vibrating member =0! 1a vibrator actuates one plate of a capacitor interposed in a tuned transformer circuit. :Hence :the 'frequencyat which the train of oscillations startin'thistuned circuit will be diiierentior each alternatepulse because of the change in ,the capacitor. associated with the reed, Therewiil thus be supplied to the-output winding of thetransformer a'irequency modulated pulse which wil-Lbe ofacharacteristic that it will be heardintelephone receiving-apparatus designed for-reception of frequency :modulated telephone current. y I shall describethreeqforms of apparatus embodying my invention and, :shall then point out the novel ieaturesnthereQrii-n:claims.3, q I In the -accompanyins drawings, :Figs. r1;and;:

re diagrammatic views showing two different of apparatus embodying my invention when used to supply pulses of frequency modulating carrier current by changes in the capacitance of a tuned circuit of a high frequency transformer. In each of the several views like reference characters are used to designate similar parts.

Referring to Fig. 1, the reference characters,

HA and LA designate a first and a second vibrator, respectively. These vibrators may take any one of several different forms, and they are shown as of the tuned reed type. The vibrator HA, for example, includes an operating winding I and a tuned reed contact member II. An operating or energized circuit is provided for the vibrator, which circuit extends from one terminal of a source of direct current, such as a battery I2, through contact [3 of a key switch K! when closed in a manner to later appear -contact I4 and contact member II of the vibrator HA and winding IU of the vibrator'to the other terminal of the battery I2. Vibrator LA is similar in construction except as to its rate of vibration and is provided with an energizing'circuit extending from battery I2 through the key contact 13, contact l5 and tuned reed contact member I5 of the vi: brator, and winding ll of that vibrator to the other terminal of battery I2. Thus with the key contact I3closed, the two vibrators HA and LA are energized and the respective reed contact members are set into vibration. The parts are so proportioned that vibrator LA vibrates at a relatively low rate and vibrator HA at a relatively high rate.

I shall assume by way of illustration that vibrator LA vibrates at a rate of say 5 times per second, and vibrator HA vibrates at a rate of 50 times per second.' Other rates of vibration can, of course. be used.

A transformer TI is' provided with a three= legged iron core structure I8. A polarizing winding l9 mounted on center leg 2I'of the core structure is energized from battery I2, current flowing from battery I2 through'key contact I3, wire 23, winding IS, a choke coil 24 and wire 25 to the other terminal of battery I2. the purpose of choke coil 24 being to prevent loss of alternating current energy in the circuit. Polarizing winding I9 is proportioned to providea predetermined flux in the iron core structure. A modulating winding 26 is also mounted on the center leg 2| of the core structure and this winding has connected across its terminals a capacitor 32 to form a tuned circuit. This tuned circuit is shock or impulse excited through a circuit including a contact of the vibrator LA and which circuit can be traced from battery I2 through key contact I3, wires 23 and 21, the tuned circuit comprisingwinding 25 and capacitor 32, wire 28, contacts 29 and 30 of vibrator LA when contact member I6 swings to the right as viewed in thedrawing, and wires 3| and 25 to battery 52. This tuned circuit is tuned to resonance at a predetermined modulated frequency and which frequency I shall assume by way of illustration to be an audio frequency of 1000 cycles per second. Thus each vibration of the vibrator LA, contact 29-30 is closed and the tuned circuit is impulseexcited from the battery I2 with the result that oscillations flow in the tuned circuit during the period of each vibration that the contact 29- -30 of the vibrator is open. It'follows therefore that the flux of the core struc- 4 ture is varied by the oscillations flowing in winding 26 and such variation is increased by proper proportioning of the flux created by the polarizing winding I9.

Two coils 33 and 34 are mounted on outside legs 20 and 22, respectively, of the core I8 of the transformer and are connected in series to a capacitor 39 to form a, tuned circuit, and which tuned circuit is impulse excited by the operation of vibrator HA. A current impulse is supplied to this tuned circuit through a circuit including battery I2, key contact l3, wires 23 and 3", the

V tuned circuit, wire 36, contacts 31 and 38 of vibrator HA when the contact member I I of that vibrator swings to the right as viewed in Fig. 1, and wires 3| and 25 to battery I2. I shall assume by way of illustration that this tuned circuit includand capacitor 32.

ing coils 33 and 34 and capacitor 39 is tuned to resonance at a carrier frequency of 100,000 cycles per second. Thus each vibration of the vibrator HA, the tuned circuit is impulse excited and a train of oscillations persists in the circuit during the period of each'vibration that the contact 3I38 of the vibrator HA is open. The frequencies of this train of carrier oscillations will depend upon the superposed flux in the iron core, and which flux is varied with the audio frequency of 1000 cycles per second due to the impulse excitation of the tunedcircuit including winding 25.

Consequently the carrier oscillations will be frequency modulated at the audio frequency oscillations. I

There is a fourth or output winding 9 mounted on the core structure 18 of transformer TI and this output winding 9 is connected to a transmitting coil 40 through a capacitor M, coil 40 being in turn coupled to a transmitting circuit or medium (not shown) of telephone system with which the apparatus of the present invention is associated. For example, in a train telephone system of the carrier inductive type disclosed in my Letters Patent of the United States No. 2,064; 642 granted December 15, 1936, for Railway train communication system, the ,coil 40 would be mounted on a train for inductive relation to the track rails and line wires paralleling the track.

Since there is no fixed phase relation between the two vibrators LA and HA the high energy component of the carrier frequency at the beginning of a pulse will be sent out at carrier frequency varying over the range determined by the change of the inductance of the transformer TI in response to the excitation of the audio frequency tuned circuit including the winding 26. It is to be seen therefore that the load circuit including the transmitting winding 40 receives a rapid succession of pulses of frequency modulated current. Also, on the assumption that the carrier frequency of these pulses corresponds to the carrier frequency of the associated train telephone system, these .pulses will be heard in the loud-speaker of the receiving apparatus of the telephone system. That is to say, that whenever key KI is actuated to close contact l3, the tuned vibrators LA and HA are powered and current impulses are supplied to the tuned circuits and the load circuit including transmitting coil 40 receives a rapid succession of pulses of frequency modulated carrier current, and which pulses will be sounded in the loud-speaker of the receiving apparatus associated with the load circuit. The sound or tone heard in the loud-speaker will have three characteristics, one depending upon the rate at which the keycontact I3 is closed and opened, another upon the rate of operation of eeiizeiie goiftiieffvipiatbr CA is Er} .12 .wheiilkey 1 is actulsg. the ciicuitincluding.

dis ed mediee heii un ee- 8. c

ycontactfli; the tunedas; memb fi i t e b s tter [2. That is to say, i is, impulse. excited; twice. each Qngvterin 4 iiipretZ r The tuned circuit i;-whee. zc omprisin trans rms-windin en -the. ca-

" peci ers..52:;-and..53eis-, tuned. to. resonance at a, predetermined: carrier.,.frequency whichv I shall 39;; plate liaboficapaciton 53. occupies the position cor responding .toythat shownin the drawing. The

. 1. 5- Qner twn: 0f hemicmphone fii resonantirequency ofithe tuned circuit is varied The/t el he Q i.ntzil winet h oughtheewind g i between a,, maximumiandi a. minimum value by, "Amened;accurate;qe res qnflin itqttheifitee. theemovementofitheiplate. 6|. of capacitor 53.

que ies; Q un n ki, a d. which. irequencm 35;; Hence,.the fneqluencyetwhich the pulses ortrains.

I-shall-aassumii t0be nau ii :"flg q ncy ofr10(10; of:oscillation-startein thei tuned. circuit will be yclee-pen-secendz. Such variations.ofi' theicure. difierentieachvaltemate excitin im ulse because rent flowing throughewindingj flgs of: the trans. oietheifchang eein .then'capacitorifil There will icrmenT'la causeicoritespondingwvariations in the thus-bepresentlin.theioutputwinding M. of transfluxfsuperimposed; in the.coreiofntheitransfonmer; 49-. former 3,...frequency -modulated- .electromotive andeintum cahuseithelpermeabili-tyeoi theitranss. force, Winding 64 .is.c0nnted; to titansinitting. farmer cores to be varied -."due.'t0.1 the current.- coil 40 coupled tothetransmitting circuit of. the thnoughthewinding M -riSinQ-e d mI-Hnstin st m associated telphone...system, the szime as ex wlththeeopexaition: 0f: the: inicrophoneila. v plaineiieimconnectioniwithFigsI1 and2.

n pu W n g 9 :05 transformer I l of 45, It isitobeseerrthei'efore that withthe appa- Fig; 2=:is;- connected:to transmitting. coil: MkthemtusmfFi 3; successive pulses of a frequency sameiasinFig. 1:,- except capacitor d-l is connectmodulatede'carrien current arexsupplied to the eel-dumixlti-ple'wlththewindingeflki transmitting-circuit forisoiinding a corresponding It is toJbe seen that in Eig. 2; theclosing iof tonein the-iouds-speaken of the receiving appethe key-c0ntact- B causes the tu'ned: clrcult-dn- 50, ratushassociatediwith such transmittingfcircuit.

cludingcwinding 33+3kof transformer T-L to bei .Although L-have. herein shown and. described impulse excited through: theaoperation of the: only. threeiiormsxofi means .fon supplying pulses vibrator- HA and 1 the. carrier: frequency oscillaoi imodulzited current) embodying my invention, tions cf-thls-tunewcircuit to belirequencmmodu itaisfiundersto dithati various. changes and modilated-at the:.a,udio= frequency. variationsi of the 55,: ficatiqnsemayibeimade. therein. within the scope permeability of the transformer.) as" causeck ofithe. appendedeclaimsiwithoutdeparting from through the operationofthe.deviceiMI-I; C'onse-. thespiritfandrscopeofmyiinvention. quently;there are supplied; torthe. transmitting: Having thus described my invention, what I coll: M1 pulses. 0t frequency modulated: carrier claimisz. current which are capableiofi'being;-tra,nsmitted 1:" Incombination, atunedzcircuit tuned to resthroughtheitransmittingcircuit ofanassociatect onance at a definite: carrier. frequency, means communicatlonasystemend aniaudio tone sounde includin'ge. ourrentisourcezanda} vibrator coned in the loud speaker of receiving apparatus ofi nected. to said.- circuit. to. periodically impulse any station of the associated: communication excite;thecircuit tolczeateisuccessive pulses of said system, (i5: cams-ism current, means in cluding an oscillating Referring to Fi 3., iaituned ci c including; member: to-var y the-ractariceof'said tunedcirprimarywinding 5.! of-riii-transformer T7." and; cult toifirequencymociulate saidpulses. of. carrier cepec tqrsitanciiai multipieieimpumeexciteocurrent. andaa, loadrelementelectrically coupled by" :u rc11tvv impulses supplied. from. betteiw I12 toithetuned: circuit to receive said pulses of ire th r ugh @vibrater-GA; Vibrator. GA isl of: the m quency,modulited cairieiicurrent. tunegl; lter-peter type having an operating; winchv Incembination; etuned. circuittuned to resing-itahqil a, tuned-re contact memberV SS. onance. eta, definitescarrier frequency, a vibrator eu gilia gy-cqntactmember 5.61pivotedat51is oper.; operable. at a definite rate. ofvibration, circuit etively atteiched totheereedncontact, memben 55; means includingi'a. contactof said vibrator andth ough;ecognectionitidicated ccnventionallybx '55. a dlrectcuri entisourc. connected to saidtuned circuit to successively impulse excite-the tuned circuit to create successive trains of oscillations of said carrier frequency, modulating means including a vibrating member, and said modulating means related to said tuned circuit in such a manner as to vary the reactance of the tuned circuit at a rate corresponding to the rate of the vibra tions of said vibrating member whereby said trains of oscillations are frequency modulated.

3. In combination, a tuned circuit tuned to resonance at a selected carrier frequency, an interrupter having a circuit closing contact member and motor means to actuate said contact member to close a contact at a selected rate, circuit means including a direct current source and the contact of said contact member connected to said tuned circuit to impulse excite the tuned circuit at said selected rate to create in the tuned circuit pulses of said carrier frequency current, modulating means having a vibrating member and motor means to actuate the vibrating member at a selected rate, and said modulating means disposed to vary the electrical characteristics of said tuned circuit to frequency modulate said pulses of carrier frequency current.

4. In combination, a tuned circuit tuned to resonance at a selected carrier frequency, an inter-rupter having motor means to periodically close a contact, circuit means including a direct current source and said interrupter contact connected to said tuned circuit to impulse excite the tuned circuit to create in the tuned circuit a series of wave trains of said carrier frequency current, modulating means having a motor for actuating a vibrating member at a given rate, said vibrating member electrically connected with said tuned circuit to vary the reactance of the tuned circuit at said given rate, and a load circuit coupled to said tuned circuit to receive a series of wave trains of said carrier current frequency modulated due to said reactance Variation of the tuned circuit by said modulating means.

5. In combination, a tuned circuit including a winding mounted on an iron core structure and a capacitor, said tuned circuit tuned to resonance at a given carrier frequency, a first circuit means including a source of current and'a vibrator con-' nected to said tuned circuit to periodically impulse excite the tuned circuit; a second circuit means including another winding mounted on said core structure, a current source :and a vibrating member to vary the permeability of said core structure; and .a load circuit including an output winding mounted on said core structure receiving successive pulses of frequency modulated carrier current due to said impulsing excitation of the tuned circuit and permeability variation of said iron core structure.

6. In combination, a tuned circuit including a winding mounted on an iron core structure and a capacitor, said tuned circuit tuned to resonance at a predetermined carrier frequency, a first circuit including a direct current source and a vibrator connected to said tuned circuit to impulse excite said tuned circuit at a rate predetermined by the rate of vibration of said vibrator; a second circuit including a source of direct current, another winding mounted on said core and a vibrating member to vary the flux of said core structure; and an output circuit including an output winding mounted on said core receiving a series of pulses of frequency modulated carrier current due to said impulse excitation of "saidtuned circuit and flux variation of said core structure.

7. In combination, an iron core transformer,

tuned circuit including a winding of said transformer and a capacitor tuned to resonance at a predetermined audio frequency, a first circuit including a current source and a first vibrator connected to said first tuned circuit to periodically impulse excite that tuned circuit, a second circuit including a current source and a second vibrator connected to said second tuned circuit to periodically impulse excite that tuned circuit, and a load circuit including an output winding of said transformer receiving pulses of frequency modulated carrier current due to said excitation of said first and second tuned circuits.

8. In combination, an iron core transformer,

a first and a second tuned circuit including a first and a second winding respectively of said transformer, said first tuned circuit tuned to resonance at a definite carrier frequency and said second tuned circuit tuned to resonance at a definite audio frequency, a first and a second vibrator operable at a first and a second rate respectively when energized, means to at times energize said vibrators, a first circuit including a current source and a contact of said first vibrator connected to said'first'tuned circuit to impulse excite that tuned circuit at a rate corresponding to said rate of the first vibrator, a second circuit including a current source and a contact of said second vibrator connected to said second tuned circuit to impulse excite that tuned circuit at a'rate corresponding to said rate of the second vibrator, and

a load circuit including an output winding of said transformer receiving successive pulses of frequency modulated carrier current due to said excitation of said tuned circuits.

9. In combination, an iron core transformer, a first and a second tuned circuit including a first and a second winding respectively of said transformer, said first tuned circuit tuned to resonance at a definite carrier frequency'and said second tuned circuit tuned to resonance at a definite audio frequency, a first and a second vibrator operable'at a first and a second rate respectively when energized, means including a manual onerable contact key to at times energize said vibrators, a'first circuit including a current source and a contact of said first vibrator connected to said first tuned circuit to impulse excite that tuned circuit, a second circuit including a current source and a contact of said second vibrator connected to said second tuned circuit to impulse excite that tuned circuit, and a load circuit including an output winding of said transformer receiving successive pulses of frequency modulated carrier current due to said excitation of said tuned circuit and which pulses have three characteristics one due to a rate of operation of said key contact, one due to the rate of vibration of said second vibrator and one due to the rate of vibration of said first vibrator.

10. In combination, a transformer having a three legged iron core structure formed with a center leg and a first and a second outside leg, means including a direct current source and a first winding mounted on the center leg of said core to create a given flux in said core, a first tuned circuit including a first and a second coil mounted on said first and second outside leg respectively of said core and tuned to resonance at a given carrier frequency, circuit means including a current source and a first vibrator contact connected to said first tuned circuit to periodically impulse excite that tuned circuit at a rate determined by the vibrating rate of the first vibrator, a second tuned circuit including a winding mounted on the center leg of said core structure and tuned to resonance at a givenaudio frequency, circuit means including a current source and a second vibrator contact connected to said second tuned circuit to periodically impulse excite that tuned circuit at a rate determined by the vibrating rate of the second vibrator, and an output circuit including an output winding mounted on said core structure receiving a series of carrier current pulses frequency modulated at the audio frequency of said second tuned circuit due to said impulse excitation of said first and second tuned circuits.

11. In combination, an iron core transformer, a tuned circuit including a winding of said transformer and a capacitor tuned to resonance at a definite carrier frequency, a first circuit including a current source and a vibrating contact connected to said tuned circuit to periodically impulse excite said tuned circuit; an oscillator including a tuning fork, a microphone varied by the oscillations of the tuning fork and a magnet to actuate the fork; a second circuit including a second winding of said transformer, a current source, said magnet and said microphone to vary the permeability of said transformer core at a rate corresponding to the oscillating frequency of said tuning fork; and a load circuit including an output winding of said transformer supplied with pulses of frequency modulated carrier current due to said excitation of said tuned circuit and permeability variation of said transformer core.

12. In combination, an iron core transformer, a tuned circuit including a winding of said transformer and capacitance tuned to resonance at a definite carrier frequency, means including a current source and an intermittent contact device connected to said tuned circuit to periodically shock excite the tuned circuit to create successive trains of carrier oscillations in the tuned circuit; a vibrator including a tuning fork, a microphone varied by the vibrations of the fork and means to vibrate the fork; circuit means including 9, current source, said microphone and a winding of said transformer to vary the flux of saidtransformer core at a rate corresponding to the rate of vibration of said tuning fork; and a load circuit including an output winding of said transformer supplied with successive wave trains of frequency modulated carrier current due to said excitation of said tuned circuit and said variations of said core flux. I

13. In combination, a transformer, a tuned circuit including a winding of said transformer and a capacitor tuned to resonance at a given carrier frequency, a vibrator having a motor for vibrating a contact actuating member at a given audio frequency, means including a current source and contacts governed by said contact actuating member connected to said tuned circuit to impulse excite the tuned circuit, means actuated by said contact actuating member connected to said capacitor to vary the capacitance of the capacitor between a maximum and a minimum value each vibration of said member, and a load circuit including a winding of said transformer receiving current pulses of said carrier frequency modulated at said audio frequency due to said impulse excitation of the tuned circuit and said variation of said capacitor.

14. In combination, a transformer, a tuned circuit including a winding of said transformer and a capacitor tuned to resonance at a definite carrier frequency, a vibrator having a centrally pivoted member and a motor to vibrate said memher about its pivot at a definite audio frequency, circuit means including a current source and two contacts closed alternately by the vibration of one end of said pivoted member connected to said tuned circuit to impulse excite the tuned circuit, said pivoted member having its end opposite said one end connected to a plate of said capacitor to vary its capacitance between a maximum and a minimum value each vibration of said member,

and a load circuit connected to a winding of said transformer to receive successive pulses of frequency modulated carrier current due to said impulse excitation of the tuned circuit and capacitance variation of said capacitor.

PAUL N. BOSSART.

REFERENCES CITED The following references are of record in the :iile of this patent:

UNITED STATES PATENTS Number 

